It took only 20 minutes on Thursday for the Swiss 17-time Grand Slam champion to win the first set 6-1 against Richard Gasquet, whereupon the Frenchman shuffled up to the net, offered his hand, and retired, suffering with a bad back.
It was disappointingly anti-climactic but it did create the intriguing prospect of Federer facing Borna Coric, the 18-year-old Croatian who only got into the main draw as a lucky loser, but who has now become the youngest
semifinalist in the tournament's 23-year history.
Coric, described by world number one Novak Djokovic as "definitely one of the most talented players in the world right now", scored a trampling 6-1, 6-3 success over former Wimbledon and US Open champion Andy Murray.
Federar says Coric plays a little like Djokovic.
"I agree he is more into the Djokovic kind of type of player from the baseline, very steady," Federer said.
"He seems to really play up when it matters against the better players," he said.
"Regardless of the level, to beat Murray 6-1, 6-3, it's a great score . . . it's definitely a message I get," Federer said.
In fact, Murray was a long way below his best but Coric still did enough to impress, with consistent containing and counter-attacking allied to excellent focus.
The Briton was uncharacteristically disappointing both with his error ratio and in his shot selection, while his improvement in the second set was brief.
The other semi-final will be between Djokovic, who is aiming for his fifth title, and Tomas Berdych, the Czech who has been runner up here for the last two years.
Berdych has also had the best start to a year of his career, with two finals and now a second semifinal, and claims this is partly due to the influence of coach Dani Valverdu, who parted company with Murray during the
He got on top when it mattered most in a 6-3, 4-6, 6-2 win over Sergiy Stakhovsky, the Ukrainian who upset Federer at Wimbledon two years ago.
But Djokovic has beaten Berdych 17 times out of 19 and has restarted with great energy after the Australian Open triumph which brought him the eighth Grand Slam title of his career last month.
Djokovic earned himself a repeat of the final of two years ago by beating Marsel Ilhan, a qualifier from Turkey, 6-1, 6-1 in a match that lasted less than three-quarters of an hour.